If ahci_dma_set_inactive is called a while there is still a pending BH
from a previous run, we will crash on the second run of
ahci_check_cmd_bh as it overwrites AHCIDevice::check_bh. Avoid this
broken and redundant duplicate registration.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>